1. Field of the Invention
The present invention relates to a screw for fixation of a bone/tendon graft during a surgical procedure and particularly, to arthroscopic anterior cruciate ligament reconstruction.
2. Related Art
Ligament reconstruction by replacing the ligament with a tendon/bone graft is well known in the art. For instance, during arthroscopic knee surgery, a surgeon can form a tunnel through the tibia, intra articular joint and femur to receive a bone-tendon-bone graft harvested from the patellar tendon. A variety of techniques have been employed to secure the bone-tendon-bone graft, such as tying sutures over ligament buttons, staples, unicortical screw posts, or interference screws. An example of one such ligament anchor system is disclosed in U.S. Pat. No. 4,870,957, which is incorporated by reference herein.
One common example of interference screw is the self-tapping Kurosaka screw which cuts its own threads into the bone and graft. With this type of screw, the graft bone plug is sized to be smaller than the receptive bone tunnel to provide clearance for the screw to begin self-tapping and threading. However, there are many disadvantages to such types of screws. Since there is no preformed channel for the screw to enter, but rather, the screw cuts its own channel within the clearance between the bone and the graft, the screw can diverge, reducing screw thread to bone plug contact. The self-tapping operation cuts into the graft, thereby possibly causing graft damage or fragmentation. The insertion of the screw can also cause migration or translocation of the graft.
Further, the Kurosaka type screw is not well secured to the insertion device and can fall off the insertion device as well as require a K-wire insertion. The bone tunnel is usually created with an acorn type drill head which can cause cavitation of the tunnel wall and the depth of the tunnel is not controlled.